In most of the United States, Canada, and several Caribbean nations, telephone directory numbers are generally constructed according to the "North American Numbering Plan" and consist of a three-digit "Numbering Plan Area" code (often referred to as "NPA" or simply "area code"), a three-digit central office code, and a four-digit subscriber line number. The latter seven digits comprise what is generally considered to be a "local telephone number", and with some exceptions, this local telephone number is what a subscriber located is within a particular area code must dial in order to reach another subscriber within the same area code.
NPA codes were originally assigned in 1947 to states, metropolitan areas, or other geographical regions. The boundaries of NPA regions were typically aligned with existing political or natural boundaries. Over time, a small number of NPA codes have been assigned to particular services without regard to geographic significance. Within an NPA, central office codes are unique. As a result of restrictions on digits in certain positions, and several codes reserved for special services, there are 792 central office codes potentially available for use in each NPA, and therefore there are 7,920,000 unique telephone directory numbers theoretically available for use in each NPA.
In recent years, a dramatic increase in the subscription to and use of telecommunications services has created an explosion in demand for telephone directory numbers. New paging and mobile telephone services are relatively inexpensive compared to historical rates and have been widely adopted by users. Improved modems, printer technologies, and telecommunications networks have fostered significant increases in the use of facsimile machines. The unprecedented growth of the Internet has created demand for additional telephone lines, or equivalent capacity, from Internet Service Providers and from Internet users. All of these services require unique telephone directory numbers. Moreover, in the United States, recent changes to telecommunications laws have allowed competitive local exchange carriers ("CLECs") to request directory numbers for assignment to their subscribers. Directory numbers are often assigned to a CLEC in blocks of 10,000 numbers, even if the carrier's actual need for directory numbers is a tiny fraction of the block.
As a result of these factors, the available telephone numbers within many of the originally assigned NPA regions have been exhausted. Telecommunications service providers and others have been forced to "split" or subdivide an NPA, or to provide some other type of relief, in order to maintain the availability of telephone numbers for new subscribers, new services, and new carriers. Even after initial relief, demand for additional telephone numbers continues, and therefore further splits or other relief are often soon required. For example, the Chicago, Illinois metropolitan area, which had a single area code as late as 1989, has five area codes as of the filing of this application, and plans are underway to add a sixth. The State of Florida, which had three area codes as late as 1988, has eleven area codes as of the filing of this application.
When an NPA split occurs, typically some portion of the geographical territory in one or more existing NPAs is defined to be in a new NPA, an available unused NPA code is assigned to that territory, and whatever territory was not selected for the new NPA retains the code or codes of the existing NPA or NPAs. Typically, but not necessarily, a single existing NPA is split into two NPAs, and the territory of the new NPA is selected such that about half of the central office codes in the existing NPA geographical region are located within the boundaries of the new NPA. Multi-way splits and NPA boundary realignments are also possible. Certain other types of relief are available, such as an NPA overlay, in which one or more area codes are added to overlay the territory of one or more existing NPAs (or a subset thereof).
One characteristic of any plan for relieving telephone directory number exhaustion involving an NPA split or other NPA boundary realignment (which events will hereafter be collectively referred to as an "NPA split") is that a substantial fraction of the subscribers (and therefore a sizable absolute number thereof) originally located within the existing NPA will, as a result of the relief, be located in a different NPA and thus will have a different area code. (NPA overlays usually do not share this characteristic because the overlay area code usually is assigned only to "new" subscriptions, and therefore the addition of the overlay area code does not directly require the area codes of existing subscriptions within the overlay area to change).
In order to assure an orderly transition to the new area code, NPA splits are typically executed in several phases to allow affected subscribers, and those with whom they communicate, to update their records of telephone numbers, to perform any required modifications to customer-owned networks, and to otherwise adapt to the new area code. In a first phase, the new NPA is announced to the public, and a permissive dialing period (PDP) beginning some months in the future, and ending some additional months thereafter, is declared. Before the PDP begins, telecommunications carriers make necessary modifications to their networks to accommodate the new area code.
In a second phase--during the PDP--calls to subscribers in the new NPA may be placed using either the old area code or the new area code. For example, when the 312 area code was split in 1989, a new NPA, 708 was designated, which was assigned to a portion of the territory originally in the 312 area code. During the PDP, calls to that territory could be dialed using either area code 312 or 708.
In a third phase--after the PDP ends--the NPA split is complete. Central office codes which previously were in use in the existing NPA, but were allocated to the new NPA, are now effectively unused in the existing NPA, and thus telephone directory numbers using those central office codes are now available for assignment in the existing NPA. Similarly, central office codes which previously were in use in the existing NPA, and were not allocated to the new NPA, are unused in the new NPA, and are now available for assignment. Such assignment would not be possible during the PDP, because calls using either of the old or new area codes would terminate at the same number. Moreover, once the PDP ends, calls to the new NPA must be placed using the new area code. Calls which are attempted using the old area code to a telephone number which has been "moved" to the new NPA are routed to the old NPA, and typically will reference a telephone number which has not yet been assigned in the old NPA.
A change to the area code of a subscriber requires corresponding changes to records of the telecommunications service provider regarding that subscriber and the subscribed services. Changing such records in the context of an NPA split poses significant technical problems for several reasons: records regarding a large number of subscriptions (possibly in excess of four million) must be updated in a coordinated fashion; for each subscription, many records relating to various functions and services, and residing in different locations, may need to be updated, also in a coordinated fashion; and availability requirements in telecommunications networks are extremely rigorous, so that services for the affected subscribers must remain substantially continuously available before, during, and after the NPA split, including during periods within which the aforementioned record updates are performed.
Among the records which must be updated in the context of an NPA split are various records used to provide certain advanced telecommunications services through what is commonly referred to as the "Intelligent Network". As is known, the Intelligent Network has been implemented by supplementing the switching, signaling, and transmission elements of traditional telecommunications networks with a plurality of interconnected and cooperative adjunct elements which provide database, information processing, and signal processing services to a telecommunications network.
An example of a service provided through the Intelligent Network is the popular "toll-free" inbound telephone service, wherein calls to special area codes (e.g. 800, 888, 877) are completed without charge to the calling party (but are paid for by the called party). As these services are currently implemented, the telephone numbers in these special area codes are not assigned to "real" telephone lines. Instead, each of these special telephone numbers are associated with one or more conventional telephone directory numbers which are to receive calls placed to the special number. When a call is placed to one of the special numbers, a database inquiry is performed using components of the Intelligent Network to determine an associated telephone directory number, and the call is directed to that number.
Another service provided through the Intelligent Network is the Caller-Id with Name service. When a call is placed to a subscriber of that service, a database inquiry is performed using components of the Intelligent Network to retrieve the caller's name, employing the supplied calling line identification as a key.
Both of the aforementioned services contemplate the presence of one or more databases having records containing telephone directory numbers which would be affected by an NPA split. The above-described services are merely two examples of many which may be provided through the Intelligent Network, and a large fraction of such services employ directory numbers which would be affected by an NPA split. Moreover, as known in the art, the components of the Intelligent Network, including the databases contemplated by the exemplary services, and others, may be widely distributed throughout the network of a telecommunications provider, and such components may also be replicated to achieve fault tolerance or desired levels of performance. Thus, in the environment of the Intelligent Network, a change affecting only a single telephone number may affect a plurality of different services and could require updates to a plurality of fields, records, or tables, in a plurality of databases, in a plurality of locations. Accordingly, when an NPA split occurs, all of these databases must be properly updated in a coordinated fashion without disrupting the services provided by the Intelligent Network.
In order to facilitate the task of creating and maintaining the various databases used in the Intelligent Network, in response to ordinary, day-to-day orders for service received from customers and to other required changes, telecommunications systems suppliers have developed "service management systems" (SMSs). An example of an SMS is the Lucent Technologies Service Management System, which is a product of the assignee of the present application. SMSs are typically implemented using general purpose computer systems (or networks thereof) and are typically connected via a suitable network to the Intelligent Network components for which they are responsible. The SMSs are responsible for receiving service order and other transactions from telecommunications service provider personnel, responsively maintaining a "golden" or record copy of each database, and causing any changes made to the golden copy of such databases to be propagated to Intelligent Network components which use such databases.
Although SMSs have proven to be useful systems for, inter alia, updating databases in the Intelligent Network in response to day-to-day transactions and events, each of these transactions typically involves a small number of records. SMSs ordinarily do not perform large-scale, coordinated updates, involving extremely large numbers of records, as would be required when an NPA split occurs. Instead, telecommunications service providers have relied on several labor-and resource-intensive processes to update the Intelligent Network databases.
In particular, prior to the beginning of the PDP, each Intelligent Network component, and each associated database, which may be affected by the NPA split must be manually identified by a person with subject-matter expertise in the content and format of the databases. In each identified database, each record containing data which would be affected by the NPA split must be identified, a second copy of each such record must be prepared, the NPA code fields in the new records must be updated with the new NPA code, and the new records must be inserted into the database. This allows calls to be placed using either of the old or new area codes. Although the processes of creating and updating the duplicate records may be automated, the task of establishing such automated processes requires further subject-matter expertise regarding the databases. Moreover, the creation and use of duplicate records is expensive in terms of processing and storage resources, both during the creation process and during production use.
Prior to the end of the PDP, each of the original records affected by the split, and which contain a reference to the old NPA (and for which duplicates were previously prepared and modified to refer to the new NPA), must be deleted from the database. This additional work thus incurs further processing and storage expense.
Accordingly, there exists a need for an improved Service Management System and associated Intelligent Network elements which cooperate to update in coordination large numbers of Intelligent Network database records, tables, or fields, and to implement Intelligent Network services based on the updated information, as required to effect NPA splits and other similar large-scale renumbering events. Although the background of the invention herein refers to certain problems experienced by telecommunications providers in areas subject to the North American Numbering Plan (NANP), it is believed that such problems are not unique to the NANP areas, and similar problems may be experienced by telecommunications providers worldwide now or in the future.